Reflow solder convection ovens are used in the production of printed circuit boards employing surface mount technology. Most convection ovens include a number of heating zones spaced along a conveyer which carries the printed circuit boards through the various heating zones. Each heating zone usually includes upper and lower heating elements, and a fan or blower associated with each heater element. The fan blows air, or nitrogen, or some other gas through the heater elements and the heater elements then heat the gas before it moves over and about the printed circuit boards.
After the heated gas passes over the printed circuit boards, various contaminants, for example, alcohol, aldehydes, ketones, acids, rosins and resins are released into the oven and carried by the oven gas flow.
These contaminants often foul the internal components and surfaces of the convection oven to the point that a thick, viscous, tacky paste or fluid or residue is deposited on certain components and surfaces. In some cases, this contamination can cause failure of various oven components. The periodic maintenance required to clean the oven internals reduces productivity.
One attempt to alleviate this problem included the use of a condenser and filter assembly and a fan which urged the contaminated convection oven gas through the condenser and filter. In practice, however, the condenser and filter fouled too quickly and too often, choking off the flow of gas and adversely affecting oven performance, until cleaned.